Improving the low-temperature activity (below 100 °C) and noble-metal efficiency of automotive exhaust catalysts has been a continuous effort to eliminate cold-start emissions, yet great challenges remain. Here we report a strategy to activate the low-temperature performance of Pt catalysts on Cu-modified CeO2 supports based on redox-coupled atomic layer deposition. The interfacial reducibility and structure of composite catalysts have been precisely tuned by oxide doping and accurate control of Pt size. Cu-modified CeO2-supported Pt sub-nanoclusters demonstrate a remarkable performance with an onset of CO oxidation reactivity below room temperature, which is one order of magnitude more active than atomically-dispersed Pt catalysts. The Cu-O-Ce site with activated lattice oxygen anchors deposited Pt sub-nanoclusters, leading to a moderate CO adsorption strength at the interface that facilitates the low-temperature CO oxidation performance.
26 October 2017 in Journal of Vacuum Science & Technology A
Tailoring catalysts with atomic level control over active sites and composite structures is of great importance for advanced catalysis. This review focuses on the recent development of area selective atomic layer deposition (ALD) methods in composite catalysts design and synthesis. By adjusting and optimizing the area selective ALD processes, several catalytic structures are developed, including core shell structures, discontinuous overcoating structures, and embedded structures. The detailed synthesis strategies for these designed structures are reviewed, where the related selective approaches are highlighted and analyzed. In addition, the catalytic performance of such structures, including activity, selectivity, and stability, is discussed. Finally, a summary and outlook of area selective ALD for catalysts synthesis and applications is given.
9 January 2017 in Angewandte Chemie International Edition
The structural, electronic, electrochemical as well as diffusion properties of Na doped phosphorene have been investigated based on first-principles calculations. The strong binding energy between Na and phosphorene indicates that Na could be stabilized on the surface of phosphorene without clustering. By comparing the adsorption of Na atoms on one side and on both sides of phosphorene, it has been found that Na–Na exhibits strong repulsion at the Na–Na distance of less than 4.35 Å. The Na intercalation capacity is estimated to be 324 mA h g−1 and the calculated discharge curve indicates quite a low Na+/Na voltage of phosphorene. Moreover, the diffusion energy barrier of Na atoms on the phosphorene surface at both low and high Na concentrations is as low as 40–63 meV, which implies the high mobility of Na during the charge/discharge process.